A sunshade tool is necessary when people go out. A common umbrella can also be used for sunshade, but is very troublesome to use because the umbrella needs to be held by a hand. Presently, there are also some backpack umbrellas jointed to a backpack or back-placed umbrellas or sunshade tools directly placed on a human body in the market. These umbrellas or similar sunshade tools are formed by only simply transferring and fixing common handheld umbrellas on the backpack or human body, which have irrational mechanism, are not attractive and practical; moreover, these tools are unable to transversely expand the sunshade width unfolded thereof, and are difficult to fold when being not in use which affect the use experience.